Demagnetizer.



No. 733,337. PATENT-ED JULY 14, 1903..

W. J. FORSTER. DEMAGNETIZER.

APPLICATION FILED MAR. 15, 1902.

N0 MODEL.

"53: nonms PETERS ca. PNGTOLITNO" wnsmuamn, u. c.

UNITED STATES Patented July 14, 1903.

PATENT DFEICE.

DEMAGNETIZER.

SIPEGIFICATION forming part of Letters PatentNo. 733,637, dated July 14,1903. Application filed March 15, 1902. Serial No. 98,278. (No model.)

- full, clear, and exact description thereof.

My invention has for its object to provide simple economical apparatushaving utility with an electrical current of sufficient intensity asmeans for demagnctizing various devices, especially watches and tools,said invention consisting in what is hereinafter particularly set forthwith reference to the accompanying drawing and subsequently claimed.

The drawing is a diagram in perspective, illustrating electric-serviceconductors and apparatus in accordance with my invention for electricalconnection with said conductors.

Referring by letter to the drawing, A indicates a spring-plug connectingpositive and negative conductors of an electric-service line, and Banother such plug connecting local circuit conductors having insulatedspring-brush terminals 0 D, the latter plug being engageable with theone aforesaid to energize the local circuit. The brushes 0 D havecontact with the hub portions of a pair of wheels E, of conductormaterial, in rigid insulated connection with a spindle F, provided witha pinion G, that meshes with a spur-wheel II, that is turned by a crankI to impart rapid rotation to the wheels, an incandescent lamp J orother resistance being put in the circuit. Each wheel E is provided withan even-number series of inwardly-projecting contact-pins at intervalsof a circle, those of one wheel alternating with those of the other.Insulated spring-brushes K L have cam end opposition to the pins of thewheels E, and the arrangement of these brushes is such that they arealternately in contact with a pair of pins of each wheel when both arein rotation, the function of the two pin-wheels on the same spindlebeing that of a pole-changer. Brush K is electrically connected tohollow-core electromagnets M N of diiferent uses, and the brush L iselectrically connected to an electric switch P, that may be closed onone or the other of electric contact points Q B, one of these pointsbeing electrically connected to electromagnet M and the other in likeconnection with electromagnet N. I-Ience either of these electromagnetscan be readily put in circuit with the pole-changer.

In practice the local circuit is closed with conductors of theelectric-service line or with a generator of sufficient electriccurrent, and one or the other hollow-core electromagnets is put in thecircuit by means of the switch, the pole-changer being then actuated tocause frequent reverses of the direction of current that goes throughsaid magnet. Each brush K L is alternately on contact pins of bothwheels E and a contactpin of one of said wheels. Hence there isalternate shunting and energization of the magnet, the frequency of thealternations being in proportion to the rotary speed of the pole-changerand number of the contact-pins thereof, this number being alwayspreferably such as will insure a cool pin of each wheel at each contactwith a brush. Shunting of the magnet throws pressure of the current intothe lamp J or other resistance to prevent the damaging sparking thatwould otherwise take place between pole-changer pins and the brushes KL, due to alternations of said current. Hence the durability of thepole-changer is insured. The lamp J as a resistance being alwaysincluded in the circuit will have full power when the magnet is shunted,but less power when said magnet is energized, the current being thendivided in said lamp and magnet, there being constant flickering of theaforesaid lamp when the pole-changer is in operation. A watch, tool, orother device that has become magnetized is placed in the hollow core ofthe electromagnet that is for the time in the circuit aforesaid anddemagnetized as a result of the above-described operation, there beingcontinuous actuation of the pole-changer while the device undertreatment is exposed in said clectromagnet. The larger electromagnct Mis designed for watches and the one N for narrow tools; but either oneof said electromagnets may be omitted and the one remaining put inpermanent electroconnection with the brushes that oppose thepole-changer without departure from what I seek to cover as myinvention.

Having thus described myinvention, what I claim as new, and desire tosecure by Letters Patent, is

1. Ademagnetizercomprisingahollow-core electromagnet, a pair ofconductor-wheels insulated on a common spindle and each provided withinwardly-extending contact-pins at intervals of a circle, the pins ofone wheel alternating with those of the other, cam end spring-brusheseach alternately in touch with contact-pins of both wheels and a singlepin of one wheel, means for electrically connecting said brushes andmagnet, means for rotating the spindle, other brushes in contact withsaid wheels, the latter brushes constituting terminals of a circuit forelectric current of suitable intensity, and a resistance in the circuit.

2. A demagnetizer apparatus comprising a plurality of hollowelect-ro'magnets different in matter of size, a pair ofconductor-wheels.

insulated on a common spindle and each provided with inwardly-extendingcontact-pins at intervals of a circle, the pins of one wheel alternatingwith those of the other, cam end spring-brushes each alternately intouch with the contact-pins of both wheels and a single pin of onewheel, a switch arranged to close an electrical circuit including eitherof said magnets and said brushes, means for rotating said spindle, otherbrushes in contact with said wheels, the latter brushes constitutingterminals of a circuit for electric current of suitable intensity, andaresistance in the circuit.

In testimony that I claim the foregoing I have hereunto set my hand, atMilwaukee, in the county of Milwaukee and State of VVis consin, in thepresence of two witnesses.

W'ILLIAM J. FORSTER.

\Vitnesses:

H. G. UNDERVVOOD, W; S. UNDERWOOD.

